Process for producing oxirane compound

ABSTRACT

A process for producing an oxirane compound from ethylbenzene hydroperoxide and an olefin in the presence of an immobilized catalyst bed, wherein the process satisfies the following conditions (1) to (4): 
     (1) the catalyst bed is divided into n catalyst beds and the catalyst beds are used in series, wherein n is an integer of 2 or more, 
     (2) fresh ethylbenzene hydroperoxide is divided into portions, which are supplied to respective inlets of the catalyst beds, 
     (3) fresh olefin is supplied to the inlet of the first catalyst bed, and 
     (4) the reaction mixture discharged from each outlet of respective catalyst beds excluding the final catalyst bed is supplied to the inlet of the subsequent catalyst bed.

This application is a 371 PCT/JP01/02188, filed on Mar. 19, 2001.

TECHNICAL FIELD

The present invention relates to a process for producing an oxiranecompound. More particularly, the invention relates to a process forproducing an oxirane compound from ethylbenzene hydroperoxide and anolefin in the presence of an immobilized catalyst bed, wherein saidprocess for producing an oxirane compound has excellent characteristicsthat it can prevent a runaway of a reaction accompanied with generationof heat and can be stably carried out under a high yield.

BACKGROUND ART

Techniques for producing an oxirane compound from ethylbenzenehydroperoxide and an olefin in the presence of an immobilized catalystbed have been publicly known. Since the reaction producing an oxiranecompound from ethylbenzene hydroperoxide and an olefin is an exothermicreaction, there have been problems that the reaction accompanies asudden generation of heat in the immobilized catalyst bed, therebymaking difficult a stable run, and sometimes not only the catalyst isdeteriorated but also the yield is lowered.

DISCLOSURE OF INVENTION

An object of the present invention is to provide a process for producingan oxirane compound from ethylbenzene hydroperoxide and an olefin in thepresence of an immobilized catalyst bed, wherein said process forproducing an oxirane compound has excellent characteristics that it canprevent a runaway of a reaction accompanied with generation of heat andcan be stably carried out with a high yield.

Namely, the present invention relates to a process for producing anoxirane compound from ethylbenzene hydroperoxide and an olefin in thepresence of an immobilized catalyst bed, wherein the process satisfiesthe following conditions (1) to (4):

(1) the catalyst bed is divided into n catalyst beds and the catalystbeds are used in series, wherein n is an integer of 2 or more,

(2) fresh ethylbenzene hydroperoxide is divided into portions, which aresupplied to respective inlets of the catalyst beds,

(3) fresh olefin is supplied to the inlet of the first catalyst bed, and

(4) the reaction mixture discharged from each outlet of respectivecatalyst beds excluding the final catalyst bed is supplied to the inletof the subsequent catalyst bed.

BRIEF DESCRIPTION OF THE DRAWING

FIGS. 1 to 3 show examples of embodiments for practicing the inventionand

FIG. 4 shows an embodiment according to Comparative Example 1.

1. catalyst bed, 2. fresh ethylbenzene hydroperoxide, 3. fresh olefin,4. Cooling equipment

BEST MODE FOR CARRYING OUT THE INVENTION

Examples of the olefin used in the present invention can includepropylene, hexene, octene and the like. When propylene is used as theolefin, propylene oxide is obtained as the oxirane compound.

The catalyst used in the present invention can include atitanium-containing silicon oxide catalyst and the like. Among them, atitanium-containing silicon oxide catalyst is preferred from theviewpoint that it allows attainment of a high yield and a highselectivity.

The process for production according to the present invention satisfiesthe following conditions (1) to (4):

(1) the catalyst bed is divided into n catalyst beds and the catalystbeds are used in series, wherein n is an integer of 2 or more,

(2) fresh ethylbenzene hydroperoxide is divided into portions, which aresupplied to respective inlets of the catalyst beds,

(3) fresh olefin is supplied to the inlet of the first catalyst bed, and

(4) the reaction mixture discharged from each outlet of respectivecatalyst beds excluding the final catalyst bed is supplied to the inletof the subsequent catalyst bed.

The condition (1) is to divide the catalyst bed into n beds and use themin series. The expression “use in series” means a connection of catalystbeds in which a reaction mixture from an outlet of a certain dividedcatalyst bed is supplied to an inlet of the subsequent catalyst bed andfinally a reaction mixture is obtained from an outlet of the n-thcatalyst bed. Additionally, n is an integer of 2 or more and is usually2 to 20. Methods for dividing the catalyst bed for distributing the heatof reaction include a method in which independently placed n reactorscontaining the catalyst are used (FIG. 1), a method in which catalystbeds are placed in partitions in one reactor (FIG. 2) and the like. Thedivided catalyst beds may be the same or different in the kind or amountof the catalyst charged.

The condition (2) is to divide and supply fresh ethylbenzenehydroperoxide to respective inlets of the catalyst beds (see FIG. 1 andFIG. 2). The term “fresh ethylbenzene hydroperoxide” means ethylbenzenehydroperoxide supplied from outside of the system constituted accordingto the present invention.

The condition (3) is to supply an fresh olefin to an inlet of the firstcatalyst bed (see FIG. 1 and FIG. 2). The term fresh olefin means anolefin supplied from outside of the system constituted according to theinvention. It is preferred that the total amount of the fresh olefin issupplied to an inlet of the first catalyst bed, but a part of the fresholefin may be divided and supplied to other place(s) than the inlet ofthe first catalyst bed insofar as the effect of the present invention isnot deteriorated.

The condition (4) is to supply the reaction mixture discharged from eachoutlet of respective catalyst beds excluding the final catalyst bed tothe inlet of the subsequent catalyst bed (see FIG. 1 and FIG. 2). Inother words, the reaction mixture discharged from an outlet of acatalyst bed serially passes through catalyst bed(s) in order. Apart ofthe reaction mixture discharged from an outlet of a catalyst bed may berecycled to the inlet of the same catalyst bed insofar as the effect ofthe invention is not deteriorated. This is effective for preventing arise in temperature caused by the heat of reaction in the catalyst bed.

By satisfying the above-described conditions, the present inventionrealizes the effect that a runaway of reaction accompanied by generationof heat can be prevented and an oxirane compound can be stably producedwith high yield. In other words, it allows suppression of lowering inthe catalyst activity by thermal deterioration, shortening of thecatalyst life, lowering in the yield, runaway of the reaction and thelike due to generation of heat accompanied by the reaction ofethylbenzene hydroperoxide and an olefin. Since the epoxidation reactionbetween ethylbenzene hydroperoxide and an olefin generates very abundantheat and is highly temperature-dependent, the reaction has a high dangerof reaction runaway. Generally, the amount of reaction has been adjustedby controlling the temperature at the inlet of the catalyst bed or bycompulsorily removing heat from the outside. However, it has becomedifficult to set the reaction temperature with accuracy according to theactivity of a specific catalyst owing to a change in the catalystactivity with time or difference in time between the outlet and theinlet of the reactor, and therefore, not only problems arises that theactivity of the catalyst is lowered and the yield decreases due tosudden increase in the amount of reaction and outflow of unreactedorganic peroxide, but also there is a problem in stable operation.According to the present invention, the rise in temperature by the heatof the reaction can be controlled by partitioning the catalyst bed andadjusting feeding amount to respective catalyst beds; therefore, itbecomes possible to prevent lowering in the catalyst activity anddecrease in the yield accompanied by sudden rise in temperature in thecatalyst bed, and additionally, the runaway of the reaction by a rise inthe reaction temperature. In the present invention, a heat-removingapparatus such as a heat exchanger may be equipped between catalystbeds. This allows control of the temperature at the inlet of eachcatalyst bed, and together with the control of feeding amount ofethylbenzene hydroperoxide, provides double-safety and -steadyoperation.

Furthermore, a catalyst bed without a feed of fresh ethylbenzenehydroperoxide may be placed subsequent to the last divided catalyst bed.This is effective for treating unreacted ethylbenzene hydroperoxide inthe reaction mixture discharged from the outlet of the last catalystbed.

The epoxidation temperature is generally 0 to 200° C. and preferably 25to 200° C. The pressure may be any pressure sufficient to keep liquidstate of the reaction mixture. Generally, the pressure is advantageously100 to 10,000 kPa. The amount of an olefin fed is 1 to 100 times,preferably 3 to 50 times, more preferably 5 to 20 times, based on thetotal molar number of ethylbenzene hydroperoxide fed to catalyst beds.Usually, unreacted olefin is recycled after separation and purificationand used as the raw material for the epoxidation reaction.

In a specific example of the reaction, a case wherein propylene oxide isproduced from propylene and ethylbenzene hydroperoxide is describedbelow. The reaction can be carried out in a liquid phase using asolvent. The solvent is a liquid at the temperature and the pressure ofthe reaction and must be substantially inert to the reactants and theproduct. The solvent may be composed of a substance existing in asolution of ethylbenzene hydroperoxide actually used. Usually, theconcentration of ethylbenzene hydroperoxide is 5 to 50% by weight andpreferably 10 to 40% by weight. When, for example, it is a mixture withethylbenzene as the raw material, said material may be used for asolvent without adding a solvent in particular. Other useful solventsinclude monocyclic aromatic compounds (e.g. benzene, toluene,chlorobenzene, o-dichlorobenzene), alkanes (e.g. octane, decane,dodecane) and the like. When a titanium-containing silicon compoundcatalyst is used as the catalyst, propylene oxide is obtained at areaction pressure of 1 to 10 MPa and a reaction temperature of 50 to150° C. with a feed of 1 to 20 times by mole of propylene based on themolar amount of fresh ethylbenzene hydroperoxide fed. Unreactedpropylene is recycled to the epoxidation step after separation andpurification, and reused.

EXAMPLES Example 1

Referring to FIG. 3, each 2 g and total 8 g of Ti-containing siliconoxide catalyst is charged in a fixed-bed flow reactor composed of fourindependent catalyst beds, and 10 g/hour of a solution containing 30% byweight of ethylbenzene hydroperoxide is fed in 2.5 g/hour portions tothe four catalyst beds. On the other hand, 15 g/hour of propylene is fedto the first catalyst bed. The reaction mixture discharged from theoutlet of the first catalyst bed is cooled by a cooling equipment, andthe total amount is fed to the second catalyst bed together with thedivided 2.5 g/hour amount of the fresh ethylbenzene hydroperoxide rawmaterial. The reaction mixture discharged from the outlet of the secondcatalyst bed is cooled, and the total amount is fed to the thirdcatalyst bed together with the divided fresh ethylbenzene hydroperoxideraw material. The reaction mixture discharged from the outlet of thethird catalyst bed is cooled, and the total amount is fed to the fourthcatalyst bed together with the divided fresh ethylbenzene hydroperoxideraw material. The pressure at the respective catalyst beds is adjustedto 7.0 MPa, and the temperature at the inlet of the respective catalystbeds is adjusted such that the conversion of the fed ethylbenzenehydroperoxide becomes 99%. The results of reaction in this case areshown in Table 1.

Comparative Example 1

Referring to FIG. 4, 8 g of the same catalyst as that in Example 1 ischarged in a single catalyst bed, and 10 g/hour of the same solution asthat in Example 1 containing 30% by weight of ethylbenzene hydroperoxideand 15 g/hour of the same propylene as that in Example 1 are fedthereto. The pressure at the catalyst bed is adjusted to 7.0 MPa, andthe temperature at the inlet of the catalyst bed is adjusted such thatthe conversion of the fed ethylbenzene hydroperoxide becomes 99%. Theresults of reaction in this case are shown in Table 2, indicating thatthe yield of propylene decreases and produced amount of acetophenone andphenol formed by thermal decomposition of ethylbenzene hydroperoxideincreases.

TABLE 1 First Second Third Fourth catalyst catalyst catalyst catalystbed bed bed bed Total Conversion of EHP (%) 99 99 99 99 99 Yield ofPO/C3′ (%) 97 97 97 97 97 ACP/EHP (%) 1 1 1 1 1 PNL/EHP (%) 0.5 0.5 0.50.5 0.5

TABLE 2 Total Conversion of EHP (%) 99 Yield of PO/C3′ (%) 89 ACP/EHP(%) 8 PNL/EHP (%) 3 [Description for Tables] EHP: Ethylbenzenehydroperoxide PO: Propylene oxide C3′: Propylene ACP: Acetophenone PNL:Phenol Conversion of EHP: [Reacted EHP/Supplied EHP] × 100 (%) Yield ofPO/C3′: [Produced PO (mol)/Reacted C3′ (mol)] × 100 (%) ACP/EHP:[Produced ACP (mol)/Reacted EHP (mol)] × 100 (%) PNL/EHP: [Produced PNL(mol)/Reacted EHP (mol)] × 100 (%)

INDUSTRIAL APPLICABILITY

As described above, according to the present invention, a process forproducing an oxirane compound from ethylbenzene hydroperoxide and anolefin in the presence of immobilized catalyst beds, said process forproducing an oxirane compound, having excellent characteristics that itcan prevent a runaway of reaction accompanied by generation of heat andcan be stably carried out with high yield, can be provided.

What is claimed is:
 1. A process for producing an oxirane compound fromethylbenzene hydroperoxide and an olefin in the presence of animmobilized catalyst bed, wherein the process satisfies the followingconditions (1) to (4): (1) the catalyst bed is divided into n catalystbeds and the catalyst beds are used in series, wherein n is an integerof 2 or more, (2) fresh ethylbenzene hydroperoxide is divided intoportions, which are supplied to respective inlets of the catalyst beds,(3) fresh olefin is supplied to the inlet of the first catalyst bed, and(4) the reaction mixture discharged from each outlet of respectivecatalyst beds excluding the final catalyst bed is supplied to the inletof the subsequent catalyst bed.
 2. The process according to claim 1,wherein the catalyst is a titanium-containing silicon oxide catalyst.